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  1. /* package whatever; // don't place package name! */
  2.  
  3. import java.util.*;
  4. import java.lang.*;
  5. import java.io.*;
  6. import java.math.*;
  7.  
  8. @SuppressWarnings("unchecked")
  9. class NumberComparator implements Comparator<Number> {
  10.  
  11.     // Special values that are treated as larger than any other.
  12.     private final static List<?> special =
  13.             Arrays.asList(Double.NaN, Float.NaN, null);
  14.  
  15.     private final static List<?> largest =
  16.             Arrays.asList(Double.POSITIVE_INFINITY, Float.POSITIVE_INFINITY);
  17.  
  18.     private final static List<?> smallest =
  19.             Arrays.asList(Double.NEGATIVE_INFINITY, Float.NEGATIVE_INFINITY);
  20.  
  21.     public int compare(Number n1, Number n2) {
  22.  
  23.         // Handle special cases (including null)
  24.         if (special.contains(n1)) return  1;
  25.         if (special.contains(n2)) return -1;
  26.  
  27.         if (largest.contains(n1) || smallest.contains(n2)) return  1;
  28.         if (largest.contains(n2) || smallest.contains(n1)) return -1;
  29.  
  30.         // Promote known values (Byte, Integer, Long, Float, Double and
  31.         // BigInteger) to BigDecimal, as this is the most generic known type.
  32.         BigDecimal bd1 = asBigDecimal(n1);
  33.         BigDecimal bd2 = asBigDecimal(n2);
  34.         if (bd1 != null && bd2 != null)
  35.             return bd1.compareTo(bd2);
  36.  
  37.         // Handle arbitrary Number-comparisons if o1 and o2 are of same class
  38.         // and implements Comparable.
  39.         if (n1 instanceof Comparable<?> && n2 instanceof Comparable<?>)
  40.             try {
  41.                 return ((Comparable) n1).compareTo((Comparable) n2);
  42.             } catch (ClassCastException cce) {
  43.             }
  44.  
  45.         // If the longValue()s differ between the two numbers, trust these.
  46.         int longCmp = ((Long) n1.longValue()).compareTo(n2.longValue());
  47.         if (longCmp != 0)
  48.             return longCmp;
  49.  
  50.         // Pray to god that the doubleValue()s differ between the two numbers.
  51.         int doubleCmp = ((Double) n1.doubleValue()).compareTo(n2.doubleValue());
  52.         if (doubleCmp != 0)
  53.             return longCmp;
  54.  
  55.         // Die a painful death...
  56.         throw new UnsupportedOperationException(
  57.                 "Cannot compare " + n1 + " with " + n2);
  58.     }
  59.  
  60.  
  61.     // Convert known Numbers to BigDecimal, and the argument n otherwise.
  62.     private BigDecimal asBigDecimal(Number n) {
  63.         if (n instanceof Byte)       return new BigDecimal((Byte) n);
  64.         if (n instanceof Integer)    return new BigDecimal((Integer) n);
  65.         if (n instanceof Short)      return new BigDecimal((Short) n);
  66.         if (n instanceof Long)       return new BigDecimal((Long) n);
  67.         if (n instanceof Float)      return new BigDecimal((Float) n);
  68.         if (n instanceof Double)     return new BigDecimal((Double) n);
  69.         if (n instanceof BigInteger) return new BigDecimal((BigInteger) n);
  70.         if (n instanceof BigDecimal) return (BigDecimal) n;
  71.         return null;
  72.     }
  73. }
  74.  
  75.  
  76.  
  77. /* Name of the class has to be "Main" only if the class is public. */
  78. class Ideone
  79. {
  80.     public static void main(String[] args) {
  81.         List<Number> li = new ArrayList<Number>();
  82.  
  83.         // Add an Integer, a Double, a Float, a Short, a Byte and a Long.
  84.         li.add(20);         li.add((short) 17);
  85.         li.add(12.2);       li.add((byte) 100);
  86.         li.add(0.2f);       li.add(19518926L);
  87.         li.add(Double.NaN); li.add(Double.NEGATIVE_INFINITY);
  88.         li.add(Float.NaN);  li.add(Double.POSITIVE_INFINITY);
  89.  
  90.         // A custom Number
  91.         li.add(new BoolNumber(1));
  92.         li.add(new BoolNumber(0));
  93.  
  94.         // Add two BigDecimal that are larger than Double.MAX_VALUE.
  95.         BigDecimal largeDec = new BigDecimal("" + Double.MAX_VALUE);
  96.         li.add(largeDec/*.multiply(BigDecimal.TEN)*/);
  97.         li.add(largeDec.multiply(BigDecimal.TEN).multiply(BigDecimal.TEN));
  98.  
  99.         // Add two BigInteger that are larger than Double.MAX_VALUE.
  100.         BigInteger largeInt = largeDec.toBigInteger().add(BigInteger.ONE);
  101.         li.add(largeInt.multiply(BigInteger.TEN));
  102.         li.add(largeInt.multiply(BigInteger.TEN).multiply(BigInteger.TEN));
  103.  
  104.         // ...and just for fun...
  105.         li.add(null);
  106.  
  107.         Collections.shuffle(li);
  108.         Collections.sort(li, new NumberComparator());
  109.  
  110.         for (Number num : li)
  111.             System.out.println(num);
  112.     }
  113.  
  114.     static class BoolNumber extends Number {
  115.         boolean b;
  116.         public BoolNumber(int i)    { b = i != 0; }
  117.         public double doubleValue() { return b ?  1d :  0d; }
  118.         public float floatValue()   { return b ?  1f :  0f; }
  119.         public int intValue()       { return b ?   1 :   0; }
  120.         public long longValue()     { return b ?  1L :  0L; }
  121.         public String toString()    { return b ? "1" : "0"; }
  122.     }
  123. }
Success #stdin #stdout 0.12s 320320KB
comments (?)
stdin
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Standard input is empty
stdout
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-Infinity
0.2
0
1
12.2
17
20
100
19518926
1.7976931348623157E+308
1797693134862315700000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000010
1.797693134862315700E+310
17976931348623157000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000100
Infinity
NaN
NaN
null
https://ideone.com/gpeDDb
language:
Java (HotSpot 12)
created:
9 years ago
visibility:
public

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